Not quite. That gets you better mixing, but maybe Blake2 has bias in some bits, or bias in some output bits given bias in some input bits. Xor is nice in that

Not quite. That gets you better mixing, but maybe Blake2 has bias in some bits, or bias in some output bits given bias in some input bits. Xor is nice in that xor of a biased bit and an unbiased bit is an unbiased bit.